1. Field of the Invention
This invention relates to surface controlled subsurface safety valves used in the oil and gas industry, and more particularly, to an improved tubing retrievable subsurface safety valve ("TRSV") and a perforating type lockout tool.
2. Description of Related Art
It is common practice to complete oil and gas producing wells with systems including a subsurface safety valve controlled from the well surface to shut off fluid flow through a well tubing string. Frequently it is also necessary to conduct well servicing operations through a subsurface safety valve. In some instances, the safety valve can be locked open temporarily, either by using control fluid pressure or by running a shifting tool into the tubing by wireline. In other instances, such as when a safety valve malfunctions and another valve is inserted, or when a second safety valve is to be installed at a different location in the well, it may be desirable to use a shifting tool to permanently lock a subsurface safety valve in its open position.
Tubing retrievable, flapper type safety valves have previously been disclosed, for example, in U.S. Pat. No. 4,723,606. Such valves typically comprise a housing connectable with a well tubing string, a bore for communicating well fluid flow, a flapper valve mounted inside the housing for movement between open and closed positions, and an operator tube in the housing to shift the flapper valve selectively between the two positions. The operator tube normally moves in response to a control signal from the well surface, but a shifting tool can releasably engage the operator tube for movement independently of the control signal. A lockout sleeve may be mounted in the housing in tandem with the operator tube for movement between a first position engaging and holding the flapper valve open and a second position of disengagement from the flapper valve.
Subsurface safety valves including both a permanent and a temporary lock open mechanism are also disclosed, for example, in U.S. Pat. Nos. 3,786,865; 3,882,935; 4,344,602; and 4,356,867. However, the design features that enable these conventional safety valves to be locked open either temporarily or permanently in the absence of control line pressure have made the valves more complicated and expensive than is needed or desirable for all markets and applications.
The use of a punch as a perforator for well flow conductors is disclosed in U.S. Pat. No. 3,111,989. The use of a punch to create outwardly extending indentations in a flow tube for locking out a well safety valve is disclosed in U.S. Pat. No. 4,574,889. The apparatus disclosed in U.S. Pat. No. 4,574,889 does not, however, provide a path for control fluid communication with the valve bore. Nor does the apparatus disclosed in U.S. Pat. No. 4,574,889 use an outwardly extending lip created by perforation to lock the valve open.